metal surface rust beneath uneffected paint

V

vaccin

I replaced a half inch square piece of metal between the roof and the windshield mount surface , the 90 degree or return it may be called

A foot away at the leading edge of the roof a thin line of light rust formed on the metal
This was covered by what appeared to be good paint uneffected by any rust below

This would mean probably that the rust is forming from the inside, No?

I have the (car) cockpit roof panels out for delaminating issues and there appears to be minimal access for any observation

Any thoughts
 
That area of the roof is famous for rusting from the inside. You'll find it especially where a car has been in an area that goes through widely varying temp changes during the day.. car gets hot inside during sunlight, any humidity vaporizes, at night it condenses against the cool roof. Gravity takes over, water droplets go down to the low areas, starting your rust issues from inside out. To check to see how structurally sound it is, I use an ice pick. One of the best ways to find lurking rust pits coming through from the back side.
 
Hi Robert

The car did spend time in fla which goes well with your initial theory and a factory sunroof is at the high point of the roof which looks clean from the inside.

On the inside I can see a semi transparent paint or sealer a silver colour
In a few places there is what appears to be drips in this coating and when I scrape them off the metal is exposed , or could be bubbles I cant say for sure.

In one place near the leading edge of the roof on the inside again, this drip or bubble is noticeable

I tried drilling into a microhole from the outside and it seems to travel the distance the thickness of the metal

the car is a 92 300e mercedes

Could be i'm replacing part of the roof any thoughts artists
 
Sorry I misunderstood. The issues I described were more geared toward a vintage vehicle of about 40 plus years old. Sorry, not the issues you expect out of something late model, they have come a bit farther in getting paint and rust preventative measures inside the cavities. The 55 I'm working on has no paint inside anything like rockers, roof skin, etc.
 
MP&C;39622 said:
Sorry I misunderstood. The issues I described were more geared toward a vintage vehicle of about 40 plus years old. Sorry, not the issues you expect out of something late model, they have come a bit farther in getting paint and rust preventative measures inside the cavities. The 55 I'm working on has no paint inside anything like rockers, roof skin, etc.
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Seems the water may well have run down the forward roof and collected as I am seeing a repeat to my initial repair on the roof return

The company did go through a short period of cost cutting measures starting in 1995 and the bodys took a hit but the 124 model in 92 was ahead of that curve seems for the bigger picture anyway
 
I am looking at 4 inches of the forward roof and the return not something my 187 hobart would best be suited for

If I can get away with less and a series of small patches It will be a redo from what I cant see that is starting to form from the inner side
 
If I were too replace this section of the roof what would be the best tools suited for a this type of replacement.
A tig would be best likely ,
I have a donor car for a replacement piece if I can go this route
 
To do it right the rusted section needs to be cut out and replaced or replace the entire roof skin. If you have a donor you don't mind cutting up you're in good shape-it just takes time. I'm not familiar with this model so I can't offer an opinion on whether I'd section it or replace the whole skin.
 
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Drivers side sunroof and door jam

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Drivers side sunroof, door, windshield

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driver side sunroof, windshield, door jam

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drivers side rear roof with glass in

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drivers side again mid roof

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drivers again

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back to front

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The pin holes have just started to get to the pinch weld in a couple areas
On the forward edge of the roof not very evident from the pics I drilled and did some light grinding to verify these were coming from the back side or were right through to the other side.
 
Bob Hollinshead;39647 said:
To do it right the rusted section needs to be cut out and replaced or replace the entire roof skin. If you have a donor you don't mind cutting up you're in good shape-it just takes time. I'm not familiar with this model so I can't offer an opinion on whether I'd section it or replace the whole skin.
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Well I know what you mean about the familiar part, maybe the pictures show something I am not aware of or what to watch out for.

This is my first prep and paint and I did not foresee I would be getting into the roof
 
I'd section it through the center of the sunroof opening or replace the entire skin. There would be some time involved with carefully drilling welds, removing the skin and cleanup but if I was replacing the whole skin I'd glue it on-I think that would be your best route. Once the old roof skin is removed cleanup any remaining corrosion on the roof header and coat it all with epoxy except on the attachment flange where adhesive is to be applied.
 
Bob Hollinshead;39676 said:
I'd section it through the center of the sunroof opening or replace the entire skin. There would be some time involved with carefully drilling welds, removing the skin and cleanup but if I was replacing the whole skin I'd glue it on-I think that would be your best route. Once the old roof skin is removed cleanup any remaining corrosion on the roof header and coat it all with epoxy except on the attachment flange where adhesive is to be applied.
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Hi Bob Sure wish this was my 10th car

I have the factory tint in the rear screen glass which means nothing if I do not know the integrity of the metal behind it
Pulling that glass i may as well have both screens replaced of course its a special order from Daimler AG but worth it, as the glass can take all of what would normally be thrown at it

Makes for an interesting project, great thanks
 
If I were to ask what tools were required to do this job , I likely should not be taking it on, so I will not ask .

If I were to replace the forward roof including half the roof opening SRO which cut off tool would allow the 1 -2 mm tolerance for this
 
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